Although there are advanced spectral-distribution estimation methods
such as [1]}, [2]},
they require a specialized color checker or light source.
For this reason,
we compared the proposed method with
the least-squares method shown in eq. (REF )
and with Jiang's high-performance method that requires no special equipment
 [3]}.
Here, we used Jiang's method only for estimating sensitivity
since Jiang's method is not designed for estimating illumination
when sensitivity is given.
subsection2
0.5ex plus0ex minus-1ex
0.5ex plus0ex
Results
Figure REF  shows
spectral distributions of the illumination estimated by using the least-squares
and proposed methods in the case where pixel values had no noise.
Both methods estimated the illumination well.
<FIGURE>